Diagnostic accuracy of patch testing based in clinical response to contact allergen restrictions in allergic contact dermatitis
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Authors Information
1Group of Clinical and Experimental Allergy (GACE), Hospital "Alma Mater de Antioquia", University of Antioquia, Medellín, Colombia
2Academic Group of Clinical Epidemiology (GRAEPIC), University of Antioquia, Medellín, Colombia
3Technological Economics Evaluations Group, SURA Company, Medellín, Colombia
4Department of Dermatology, Hospital Arnau de Vilanova, Valencia, Spain
5Dermatological Research Center, University of Antioquia, Medellín, Colombia
History
Published: 20 February 2023
Accepted: 14 February 2023
Received: 11 October 2023
SUMMARY
Background. Patch testing (PT) is used to identify substances that cause allergic contact dermatitis (ACD). However, the clinical effects of allergen restrictions following PT have not been thoroughly investigated. This study aims to assess the diagnostic accuracy of PT in patients suspected of having ACD. Methods. Prospective study. PT were performed in patients with clinical diagnosis of ACD. Patients with a positive PT (case group) had a strict restriction of the suspected substance for one month. In patients with negative patch testing (control group), allergen restriction was based in clinical history. Clinical reduction (CR) of at least 50% in disease activity (CR50%) after one month of allergen restriction was considered clinically relevant. Total control was defined as clinical reduction of at least 90% (CR90%). Results. From 400 patients, 66.2% had a positive PT. The sensitivity of PT to identify CR50% was 84%, specificity 47%, PPV 53%, and NPV 81%. Only 10.5% of patients achieved CR90%. Conclusions. The PT had moderate diagnostic accuracy. It could be useful as a screening, but a positive result should be confirmed with controlled allergen restriction. The low number of patients who achieved a 90% CR invites to reconsider the allergens included in PT and the mechanistic processes of the disease.